The thing about Zeppelin, at least up here in the Northeast, was that you could LITERALLY hear ANY Zeppelin song from I through Graffiti on the radio at any given time, depending on the time of day, the format and the station. They weren't limited to the "hits" or the singles (which there, technically, weren't any).
WPLR in New Haven (the station I listened to most) always had blocs - you know, a "Get The Led Out" kind of thing - where they'd play anything.
I guess you have to like them to think this, but for my money, from I to Graffiti, there are only a handful of songs that are "filler". Honestly, only really "Hats Off To Roy Harper" fits that bill.
1. Stairway to Heaven
2. Going to California
3. When the Levee Breaks
4. The Battle of Evermore
5. Misty Mountain Hop
6. Rock and Roll
7. Four Sticks
8. Black Dog